This invention relates to a concrete distribution system for high pressure pumping of concrete, cement and the like in construction of roads, buildings and the like, and in particular to such a concrete pumping and distribution system having a distribution line including one or more valve units connected serially in the line with a side discharge for discharging of the concrete material intermediate the total length of the pumping line.
Concrete pumping systems are now extensively used in the laying and distribution of concrete and cement in the construction of buildings, roads and the like. In such systems, a high pressure concrete pump receives the concrete mixture and forces it into and through a line or lines from the pumping station to the depositing station. The distribution lines are generally formed from steel or flexible tubing sections interconnected to each other with quick detachable or releasable couplings. To avoid the necessity of moving the discharge end of the pipe line and/or to permit the selective distribution at multiple points along the distribution line, the high pressure pumping line may be provided with a "dump" valve means at appropriate intermediate locations in the line. For example, U.S. Pat. No. 2,021,108 which issued Nov. 12, 1935 and U.S. Pat. No. 2,092,961 which issued Sept. 14, 1937, disclose similar side-discharge gate valves adapted to be interconnected within a concrete distribution line for purposes of discharge at an intermediate point along the pumping line. The gate valve heretofore has generally been constructed with a valve cover essentially corresponding to the tubular configuration of the pumping line. In the closed position of the gate valve, the valve presents a smooth continuation of the flow path within the pump line. Thus, the workers in the art of concrete pumping have generally considered a smooth, continuous path of substantial importance to avoid buildup of concrete within a pocket in the line. Pumping of the concrete and the like normally uses pumps operating at pressures of 500 PSI and above. In addition, surge pressures of greater magnitude are encountered in the system. Although intermediate dump valves provide convenient deposit of the mixture, it has been found difficult to create a highly effective seal of the valve in the presence of high pumping pressures.
the present invention is particularly directed to an improved valve for concrete pumping apparatus and the like having an improved seal structure particularly based on the realization that in many instances an offset chamber or pocket of a relatively small size is acceptable.